1. Field of the Invention
The present invention relates to a ferroelectric liquid crystal apparatus and a method for driving the same and, more particularly, to a ferroelectric liquid crystal apparatus characterized by a driving waveform applied to a scanning electrode of a ferroelectric liquid crystal panel, and a method for driving the same.
2. Description of the Related Art
When a scanning electrode driving circuit for a ferroelectric liquid crystal apparatus is constructed in an integrated circuit form, the chip size becomes larger as the breakdown voltage of the integrated circuit is increased. To address this, it is known to use a swing power supply as a power supply that can substantially halve the breakdown voltage required of the integrated circuit. Swing power supplies are widely employed for use in super twisted nematic (hereinafter abbreviated STN) panels and active matrix panels (called MIM active panels or TFD active panels) having two-terminal switches. An example of application to a ferroelectric liquid crystal panel is described in Japanese Unexamined Patent Publication No. S62-237432.
As will be described in detail later with reference to FIGS. 1 to 7, the driving method of the ferroelectric liquid crystal apparatus has the following problem. That is, as the liquid crystal layer in the ferroelectric liquid crystal panel is thin and the relative permittivity of the ferroelectric liquid crystal is very large, a parasitic load of large capacitance exists on each scanning electrode. As a result, when a swing power supply is used, electric charge stored in a pixel is discharged and a pulse edge describes a time constant curve, causing a significant change in the shape of the driving voltage waveform. When the scanning electrode driving circuit is constructed from an integrated circuit, this change in the driving voltage waveform shape may lead to a breakdown of the integrated circuit.